As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT NR 3111 - PHL-LYH - ON APPROACH TO LYH, SELECTED GEAR DOWN AND GEAR FAILED TO EXTEND. THREE UNSAFE LIGHTS WERE ILLUMINATED. THE CREW PERFORMED THE ALTERNATE EXTENSION AND LANDED IN LYH WITHOUT INCIDENT. REMOVED AND REPLACED THE LANDING GEAR SELECTOR VALVE.